The invention relates to a method for after combustion of reaction gases resulting from the decarburization of liquid steel in reaction vessels under vacuum.
In DE 41 30 590 C2 a degassing vessel is provided as a reaction vessel for the vacuum treatment of liquid steel. In this printed document it is disclosed that particles are entrained by a degassing current of the reaction gases which leads to a pronounced deposit formation of steel splashes in the upper part of the reaction vessel and in the area of the connecting line to the vacuum pump. Such steel deposits may have a considerable weight and finally may almost close off the upper end of the reaction vessel so that, in general, such steel deposits must be removed in a complicated manner by melting.
For avoiding the formation of such steel deposits, a method is suggested in EP 0 347 884 B1, which defines the closest prior art, to the instant invention with which an after combustion of the resulting reaction gases is desired. In the context of this known method, oxygen or an oxygen containing gas is blown via a pipe insertable to a defined spacing above the surface of the liquid steel within the steel bath in an amount to be calculated. With this known method three effects are to be achieved jointly, i.e., the decarburization of the steel by supplying oxygen, a heating of the steel bath, as well as an after combustion of the reaction gases resulting from the vacuum treatment. In practice, it was shown that with the known method the prevention of steel deposits especially in elongate, respectively, tall reaction vessels cannot be prevented sufficiently reliably.